The recent proliferation of electronic text and multimedia databases has placed at society's fingertips a wealth of information and knowledge. Typically, a computer is employed that locates and retrieves information from the database in response to a user's input. The requested information is then displayed on the computer's monitor. Modern database systems permit efficient, comprehensive, and convenient access to an infinite variety of documents, publications, periodicals, and newspapers. Yet retrieving information from databases is often slow. Sometimes, this is caused by bandwidth limitations, such as when information is retrieved from remotely-located databases over an ordinary telephone line, a very narrow bottleneck. In other cases, slow retrieval is caused by a relatively slow local mass storage device (e.g., a CD-ROM drive).
Information in the database is normally accessed through a user-generated Boolean query. As is well known in the art, a query comprises one or more search terms and connectors that define the relationship between multiple search terms. For example, a boolean query can be formulated that will find only those documents where the words “Hadley” and “Baxendale” occur in the same sentence. Another query might require that “Hadley” and “Baxendale” be found within a given number of words of each other. Other queries might restrict the search so as to require that all the search documents be published in a certain year, or range of years.
Another querying technique employs the use of a “natural language” processor. The natural language processor interprets a user-formulated query consisting of a list search terms, and then finds the most relevant documents based on a statistical analysis of the uniqueness of the search terms. “Uniqueness” is usually defined by the contents of the database.
Whatever querying technique is used, a search engine uses the query define a class of documents within the database, and locates each of the documents within the class. The user then browses the search results by “paging through” one or more of the search documents.
Although databases are capable of accommodating huge amounts of information, retrieving information from databases is much slower than retrieving information from local random access memory. In multiple-user, remotely-located databases, for example, the user typically retrieves search documents over an ordinary telephone line, which is a very narrow bottleneck. In single-user, local systems, retrieval of search documents requires that the documents be read from a relatively slow local mass storage device (e.g., a CD-ROM drive).
Consequently, today's database systems are plagued by the problem of slow document retrieval. After a query is processed and search documents are identified, the user begins browsing the search results.
There exists a compelling need for a database system that has better usability and/or a quicker response time so that information is displayed very soon after the user requests it. This need can be satisfied by effectively utilizing the time the user spends studying the information on the display screen. In a database system (or document retrieval system) in one embodiment of the present invention, information that the user is likely to eventually request is preloaded into memory while the user is viewing other information. The present invention takes advantage of the fact that it is possible to accurately predict the information that the user will eventually request be shown on the display. In some embodiments, the present invention takes advantage of the fact that it can be useful to have the user exercise some direct control over the retrieval of information. Some embodiments of the present invention could also take advantage of the fact that the time that the user spends viewing displayed information is often sufficient to advantageously preload a substantial amount of information.
With these and other objects, advantages, and features of the invention that may become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims, and to the several drawings herein.